The present invention refers to a method and means for tensioning a reinforcing member, which may be a wire, a group of parallel wires or a bar along which frictional forces occur. According to methods now used the reinforcing members are tensioned by means of a statically (slowly) working ram, being applied to one end of the member, the other end thereof being fixed. Alternatively pulling forces may be applied to both ends of the member. On both occasions the resulting tension will decrease due to friction, in a direction away from the point where the tensioning force is applied. As the influence of the reinforcement in a certain section is proportional to the tensional force in the same section, a reduced tension due to friction will mean that the reinforcement is unsatisfactorily utilized.
The aim of the present invention is to better use the strengthening bars by a method and means which eliminate the influence of friction, and provide a more constant tension in the reinforcing members, or a tension, which better corrsesponds to specific demands.